1. Field of the Invention
The present invention relates to a substrate inspection apparatus that is used in the process of manufacturing a semiconductor device, a substrate inspection method, a method of manufacturing a semiconductor device and a recording medium. More specifically, the invention relates to inspection of defects in the electrical conductivity of contact holes or via holes in interconnection, by way of example.
2. Related Background Art
In a hole-making step during the manufacture of a semiconductor device, a defect inspection method is used in the art to detect defects in interconnections, by obtaining a potential contrast image of the surface of an interconnection that is present in one specific chip on a wafer surface, then comparing the potential contrast images of the interconnection surfaces of cells which are adjacent and which are assumed to have the same interconnection thereon or comparing further potential contrast images of the interconnection surfaces of dies which are adjacent and which are assumed to have the same interconnection thereon (as described in Jpn. J. Appl. Phys. Vol. 38 (1999) pp. 7168–7172, Voltage Contrast Defect Inspection of Contacts and Vias for Deep Quarter Micron Device, by way of example).
Such a defect inspection method is generally called a cell-to-cell image comparison inspection method or a die-to-die image comparison inspection method, and a defect inspection apparatus using electron beams is also used for these methods. The cell-to-cell image comparison inspection method is used when inspecting dies that have repetitive interconnection, such as memory devices, whereas the die-to-die image comparison inspection method is often used when inspecting dies of, such as logic devices that do not have repetitive interconnection.
In this manner, with a method of illuminating an electron beam onto the surface of the semiconductor substrate and detecting fatal defects (breaks and short-circuits) in the lower layers of the interconnection from differential images of potential contrast images of the interconnection surface, it is possible to inspect defects in a defective product having an interconnection of complete breakdown and then a high interconnection resistance (of E9 Ω upward) due to e.g. presence of an insulating film at the interface of the bottom of a hole, since there is a clear difference in signal intensity between potential contrast images to be compared, which enables determination whether or not there are defects.
With respect to a defective product which has an interconnection of low resistance (of 500 to 2,000 Ω) because the interconnection is not completely broken due to e.g. tiny voids in a metallic material which fills a hole, however, a clear difference in signal intensity cannot be observed from a comparison of potential contrast images. For that reason, the inspection is difficult because it is not possible to determine defects with the use of differences in signal intensity, and thus there are problems in that not only the inspection accuracy but also the product yield drops.